Process of treating cassava and products thereof.



UNITED STATES PATENT OFFICE.

CHARLES C. MOORE, OF. WASHINGTON DTSTRIC'F OF COLUMBIA.

PROGESSOF TREATING CASSAVA PRODUCTS THEREOF.

N 0 Drawing.

' it comprises a process of producing a sugary material from cassava by treating fresh cassava in such manner as to arrest enzymic action, separating starch therefrom and evapcrating the liquid from which such starch has been separated; and it also comprises a concentrated sugary material containing the natural sugars of cassava in substantially their original ratio; all as more-fully here-. inafter set forth and as claimed.

Cassava or manioc produces a very large yield per acre of tubers rich in'total carb'o hydrates, and grows thriftily in parts of the country and upon soils where no other field crop does well, but hitherto because of inherent difliculties it has not been utilized much in the arts. lnthe fresh state, imme diately after digging, the tuberscontain from 4 to 14 per cent. of sugars or soluble fermentable matter, and 20 to 35.per cent. of starch, but these percentages rapidly decrease thereafter as the tubers at once begin to spoil' They cannot be stored and it is ordinarily impracticable to keep them over. a day or so after digging without great .deteriorat-ion. This is ordinarily ascribed to the action of bacteria and yeast, and no doubt thisv plays some part, particularly where the tubers are peeled, bruised or broken, for'the high content of sugar in thejuices makes them very susceptible of fermentation. But, as I have d'scovered, enzymic activity of the juices an tissues of the fresh tubers is much more responsible for the rapid deterioration. Cassava is rich in enzymic bodies which begin their work at once upon digging of the tubers and produce extensive" and far-reaching changes in the tissues and constituents thereof. In a little time after digging, a section of a'tuber will show clearly apparent rings where tissue and constituents have been changed and altered. Certain of these enzymic bodies" produce hydrocyanic acid and cyanids, causing the wellknown poisonous nature of Specification of Letters Patent. Application filed May 7, 1910. Serial No. 559,907.

into de'xtrin and other pear to be present.

is difiicult Patented Feb. 6, 1912.

some varieties of fresh cassava. Certain other enzyms, appearing to be always present in fresh cassava, rapidly break down the starch into soluble bodies, apparently at first ill-"defined soluble bodies, which are, at least in part, of an unfermentable non-sugary nature. The cellular tissue apparently shares in this degradation. The contained sugars also tend to disappear in some manner even prior to access of yeast and bacteria. I Proteolytic enzyms also ap- Still another, and very important, action of enzymic nature, always noticed in cut or broken tubers is a blackening or discoloration probably due to the presence of a' laccase or oxidase This discoloration is a serious hindrance to the manufacture of high grade starch'and syrup from the fresh tuber.- J

Expensive experience has shown the experimenters in this field that utilization of cassava tubers more than a day or so old is Apart from substantially impracticable.

the question of supply to a factory of any large capacity, to make starch on any but the smallest scale has not-been feasible heretofore because of difliculties caused by souring and spoiling. in the starch apparatus. The stated enzymic actions rapidly convert the mater al into forms very suitable for bacterial growth. These difliculties have also prevented any utilization of the purposes. the tubers time or by attempts at the direct tubers for commercial The liquid obtained by pressing after standing a briefperiod of extraction by water'is discolored, to handle because of its change ability and does not'upen concentration ive a I good and useful syrup. The original sugars have been changed to some extent, staining dark colored bodies are present, the liquid is contamin'ted with dextrins and other non-sugary carbohydrates and the proteolytic enzyms have produced indefinite soluble proteid bodies. I have however discovered that if the enzyinic activity of the cassava be arrested,

*these difficulties disappear and it is perfectly possible to utilize both the starch andthe sugars or fermentable soluble bodies of the tubers. Cassava starch, because of its inherent advantageousproperties, is much desired in the trade and it is bestrecovered as such in lieu -of being hydrolyzed and fermented, as has been pro posed, and with such recovery in the manner hereinafter described,the natural. sugars of the tuber are left in a form available for re: covery by a simple, concentration of the liquid from which the starch has been separated. Their quantity and character make I them eminently'suitable for this purpose. Low-grade dirty starch, scums, fibers and w precipitates produced in the process may be hydrolyzed-and added to the sugary liquid. I have discovered that in order to arrest, neutralize or destroy enzymic, activity and make cassava suitable for utilization, it is necessary to comminute' the tubers as soon as practicable after diggingand treat the pulp, shreds or slices in such manner aslto prevent contained enzyms from functioning. A very simple way, ordinarily best conducted on the farm where the tubers are produced, is to rasp' or thinly slice them to 20 convert them into a finely divided form and dry at once and as rapidly as possible, consistent with a temperature lojlqfenough to be below the hydrolyzing p'gintof starch. It is frequently possible in the sunny portions of the countrywhere cassava grows. to the best advantage, to effect sufliciently rapid drying by exposing very thin or frequently stirred layers of rasped or grated cassava in trays to the direct action of sun or wind. Or the rasped or sliced cassava may be quickly dried in any of the commercial forms of low-temperature driers.-- Drying at a speed suflicient to outstrip the enzymic activity of the cassava is absolutely necessary and the comminuted tubers must not be alloweduto stand untreated. When the available facilities for rapid drying are, inadequate, I have found that .by adding soluble salts, such as common salt or alkal1 sulfites,

40 or dilute acids the activity of the enzymsis reduced andt enecessity for speed is not so great. For s me purposes, the addition of a little sodium carbonate or bicarbonate, or

the corresponding potassium salts, or even v dusted slake d lime is useful as these alkaline bodies possess a specific enzym-arresting .function in the case of-starch-hydrolyzing enzyms; Of course where'the comminuted cassava can'be treated with enzym-arresting chemicals, drying can be performed at leis: ure or omitted altogether, the wet, treated I pulpv being stored or worked up at once, Quick comminution after digging. andtreatment in some manner to arrest the activity v of the. enzyms are, -however, always necessary. And even when the fresh wet treated pulp is used in the factory operation,.in the.

.' method hereinafted described, it is usually advantageous to employ with it a certain amount of the dried ulp,.produced as described. This ,is for t e reason that in factory operations it is often desirable to work with liquids of greater concentration than that of the natural juices of'the.tubers,ysay 4 to le er cent'on the sugar scale. With preliminarydesiccation of 'at least a portion of the material, the obtaining of higher concentrations becomes possible. When dried in the manner described, with or without starch. and syrup manufacture it must ordinarily be used only with liquids arresting enzymic activity unless the starch separation be very rapid indeed. Simple drying at low temperatures does not destroy enzyms but "merely arrests their activity, and when the dried cassava is' moistened the activity of the enzyms recommences.

'In the actual operation, I usually rasp, slice or grate the cassava and then pass it between edge-stones together with sufiicient liquid to forma starch milk. Where fresh t ibers are being employed, they are best preliminarily scoured in a scouring drum ,of usual construction to remove sand and dirt.

starch milk, unless chemicals have been-employed in drying the cassava or preserving the pulp, I employ suitable chemical means to arrest enzymic activity and also fermentation. A small amount of sulfuric or hydrochloric acid will serve. Lactic acid is also suitable. Ayportion of the liquid may be allowed to sour t9 the maximum extent and employed, aftersterilization, to

acidify the rest of the material. As a rule however, I prefer to employ acid sulfites, such as calcium acid sulfites as their antienz'ymic action is good for the present purposes whilethey have an additional function in increasing the yield of starch from the dried material as more fully setforth in my copending application Ser. No. 490,411, April 16, 1909. The comminuted'tuber may be simply moistened with a solution of real- 'cium acid sulfite and dried, either in the sun or by artificial heat, producing a creamcolored dry material, free from blackening and having the contained sugars and other" bodies in substantially the same state as in the original tuber.- In this drying however the starch appears. to be ripened somewhat so that the dry material gives a rathergreateryield -than'does the fresh. In the -starch making operation the. contained su'lfites prevent enzymic action, discoloring, spoiling and changes in the. su ars while they are substantially harmless 1n the 'resultan't syrup The more rapid the starch separatlon can be made,- the-'1ess is theproortion of acid or' other chemical necessary in the starch milk. "Rapid work can be seeured by the use of starch centrifugals,

either of the continuous or non-continuous turned to the zones in thesemachines after washing may be treated in the usual manner to make mer chantable starch, The washings-may be rewater, but in any event it.is ordinarily desirablegto use some dried cassava to make up for the dilution. The liquid separated from the starch by the machine is also to be returned in part to the grinders, the remainder being sent forward for evaporation, after partial neutralization if deemed necessary. Reuse of the separated starch-liquor in starch making is eminently desirable, the

"addition oftoo much water, as stated, leading to too great a dilution of the sugar solution. Ordinary starch tables may also be used for liquor from which the starch has. been separated is used in the manner just described. the liquid is .murky with suspended coagulum, consist- Passing the starch tables,

ing of fiber, enzyms and other proteids coagulated by the acid or other chemical, and" mechanical impurities. This matter-shouldbe whirled or otherwise separated. from the liquid to clarify the same prior to return to the grlnding mill or'to delivery to the concentrators. Thesolids so separated are valuable for feed. U ing a centrifugal apparatus, this feed stu will-be found next the dirty starch layers and may be easily separated mechanically. From centrifugals the separated liquor is as a rule sufficiently which is sent to the evaporators.

clarified for use. Employing fresh cassava, which contains around 60 per cent. of water, since the starch and fiber leave the system with only about 12 per cent. of moisture by returning the extracted liquors after sep- I arating the starch, there is an evident overplus of such liquid, Without taking into consideration the" water used in washing starch, etc., and added. It is this over-plus After producing the starch milk from the dried and preserved cassava, and separating the starch therefrom,"the residual liquid is simply concentrated. It may any of the usual methods.

line with lime, the greaterpart of the sulfite can be precipitated, carrying down with it If desired carbonation can also be resorted to after adding the ,lime. In the concentration any suitbe' defecated by able type of evaporator maybe employed.

Multiple effect pans are suitable. The material may, if desired be finished in a strike pan in the usual way. The'concentration may be carried down tom syrupy consistency or to string test Graining is usually hardly practicable though some samples of cassava carry relatively large proportions of cane sugar. The syrupyproduct obtained is usually nearly white and containsthe nat ural sugars of the cassava in about the same relative proportions as the original tubers.

grinders for use in lieu of separating the starch. .Thei

On making alka Where an enzym .poison, such .as ,calcium acid sulfite, has, been employed; it usually contains more ,or less of this.

What I claim is 1; The process .of' preparing valuable products from cassava-which comprises disintegrating fresh cassava, treating to arrest .enzymic activity, preparing a starch milk containing the soluble sugars, separating the starch therefrom to form a residual liquor and preparing a concentrated sugaryr prodnot from such residual liquor.

2. The process of preparing valuable products from cassava which comprises disintegrating fresh cassava, treating to arrest en zymic activity, preparing a starch milk returned residual liquor, separating, the .starch therefrom to form residual liquor, returning a port-ion of-the residual liquorto aid in preparing fresh starch milk and evapcrating another portion of such residual liquor to obtain concentrated ucts. 3. The process of preparing valuable integrating fresh cassava, treating with enzym-arresting chemicals, preparing a starch milk containingthe soluble sugars, separating the starch therefrom to form a residual liquor and preparing a concentrated sugary productfrom such residual liquor.

4. The process of preparing valuableproducts from cassava which comprises disintegrating fresh cassava, treating with enzym-arresting chemicals, preparinga starch containing soluble sugars with the aid of sugary prodmilk containing soluble sugars with the aid of returned residual liquor, separating-the starch therefrom to form residual liquor, returning a portion of the residual liquor to aid in preparing fresh starch milk and evaporating another portion of such residual liquor to obtain concentrated sugary products. v 5. The process of preparing valuable products from cassava which comprises disin tegrat-i'ng fresh cassava, treatingwith enzym-arresting chemicals and drying, pre-' paring a starch milk from the treated cassava, separating the starch therefrom to form a residual liquor and preparing a concentrated sugary product from such residual liquor by evaporation. A

6. The process of preparing valuable products from cassava which comprises preparing a starch milk from dried cassava conof cassava comprlslng dried cassava contamlng enzymarresting chemicals, separating the starch therefrom to form a residual liquor and preparing a concentrated sugary product from such residual liquor.

8. In the preparation of valuable products from cassava, the process which comprises forming a starch milk from cassava, separating the starch therefrom in -the presence of enzym arresting chemicals to form a residual liquor and preparing a concentrated sugary product from such residual liquor.

9. Inthe preparation of valuable products from cassava, the process which comprises forminga'starch milk from a body of cassava comprising cassava dried in the pres ence of enzym-arresting chemicals, separating starch therefrom in the presence of enzym-arresting chemicals and preparing. a

concentrated sugary product from the residual liquor. a K

10.-The process of preparing valuable products from cassava which comprises disintegrating fresh cassava, treating with a bisulfite to arrest enzymic activity, preparing a. starch milk containing the soluble sugars, separating the starch therefrom to form a residual'liquor and'preparing a concentrated sugary product from such residual liquor. I I j I 11.,The process of preparing valuable products fromncassava which comprises disintegrating fresh cassava, treating with a bisulfite toarrest enzymic activity, prepar ing a starch milk containing soluble sugars with the aid of returned residual liquor, separating the starch, therefrom to form residual liquor, returning a 'portionof the residual liquor to aid in preparing fresh' integrating fresh cassava, treating with a ing soluble sugars with the aid of returned residual liquor, separatin the starch therefrom to form residual llquor, returning a portion of theresidual liquor to aid in preparing fresh starch milk and evaporating another portion of such residual liquor 'to obtain concentrated sugary products.

products from cassava which comprises dislntegrating fresh cassava, treating with a from the treated cassava, separating the starch therefrom to form a residual liquor and preparing a concentrated sugary product from such residual liquor by evaporation.

15. The process of preparing valuable products from cassava which comprises preparing aj starch milk from dried cassava containing a bisulfite, separating the starch therefrom to form a residual liquor and preparing a concentrated sugary product from such residual liquor by evaporation.

16. The process of preparing valuable products from cassava which comprises preparing a starch milk from a body of cassava comprising dried cassava containing a bisulfite, separating the starch therefrom to "form a residual liquor and preparing a concen- .cassavacomprising cassava dried in the presence of a bisulfite, separating starch therefrom in the presence of a bisulfite and preparing a concentrated sugary product from the residual liquor.

In testimony whereof, I afiix my signature in the presence of witnesses. I c i CHAREES C. MOORE.

. Witnesses:

h K. P. MoELRoY, C. W. FOWLER.

bisulfite, preparing a starch milk contain- 14. The process of preparing valuable" bisulfite and drying,preparing a starch milk ,trated sugary product-from such residual prises forming a starch milk froma body of 

